The present state of laser technology has advanced substantially from that available in prior years. For example, a variety of laser devices, including gas lasers, dye lasers and solid state lasers are available for particular customer applications. At this time, a substantial portion of the commercially marketed lasers are of the gas variety. The gas lasers available are generally limited to a laser device which produces on a single wavelength (emission line) or a single color output. For example, helium-neon laser devices which are available commercially generate only the red wavelength (i.e., 6238 A) output. Although argon ion gas lasers are available, which are capable of simultaneously producing blue and green output light, the argon gas laser is considered to be too costly, inefficient and cumbersome as far as size is concerned to have extensive commercial applications.
The laser disclosed in U.S. Pat. No. 4,021,845 produces white light (light having multiple lines) which includes three of the primary colors; red, blue and green. The laser is very advantageous since an end user has the capability of selecting the desired wavelength(s) for a particular application from a plurality of available wavelengths, the laser being relatively inexpensive and of a physical size which makes it attractive for many commercial applications.
Although the laser described in the aforementioned patent has performed satisfactorily, a more compact and controllable type of laser which can be operated at higher input density would be desirable. Further, it would be desirable if the basic configuration of the laser could be easily expandable to allow the power level for a selected wavelength to be increased depending on the type of application required. In other words, what is desired is a multiline laser device which is capable of operating at high input power density which in turn allows the power level for a particular wavelength desired to be increased, has improved stability characteristics, is compact and is cost effective while providing the multiple line output.
The gas laser of the present invention is intended to provide these additional advantages, and is characterized in that the anode means comprises a split, centrally located, short cylindrical anode and two segmented hollow cathodes located symmetrically adjacent the split anode.
The hollow-cathode gas laser of the present invention provides many advantages over prior art multi-line lasers in that the gain, current density and power loading of each laser transition can be controlled and wherein, for multicolor operation, color balancing and control is also provided.